1. Field of the Invention
The present invention relates to a communication apparatus, a communication method, a program, and a communication system.
2. Description of the Related Art
Recently, IEEE (Institute of Electrical and Electronic Engineers) 802.11n for achieving high-speed wireless communication has been studied. In the IEEE802.11n, in order to achieve transmission efficiency of MAC (Media Access Control), retransmission control schemes such as packet aggregation and selective ACK are expected to be used in combination.
In IEEE802.11n (“IEEE802.11n” The 802.11n Working Group of the 802 Committee), for a protocol used by communication apparatuses to perform bidirectional communication, a reverse direction sequence (hereinafter, referred to as an “RD scheme”) is proposed.
More specifically, the RD scheme is a scheme in which an initiator that has acquired a transmission right (access right) for a communication path, by a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) procedure, etc., performs granting of the transmission right (RD Grant; hereinafter, referred to as “RDG”) to a responder. The RD scheme enables transmission by the responder within a transmission opportunity (TXOP) acquired by the initiator and thus is effective in that the collision probability for bidirectional communication can be reduced.
Note that an IEEE802.11 MAC layer requires packets provided from an upper layer of a transmitter side to be delivered to an upper layer of a receiver side in the order that the packets are provided. Therefore, the receiver side arranges packets that have arrived in an overlapping manner or in a reverse order through varying wireless communication paths, according to sequence numbers provided to the packets by the transmitter side and then supplies the packets to the upper layer of the receiver side.